Selective nickel deposition

ABSTRACT

A process for selectively depositing nickel by irradiating selected portions of a substrate coated with an irradiation sensitive compound. Immersing the irradiated substrate in a developer deposits controlled amounts of nickel in the selected portions.

United States Patent Philipp et a1. Apr. 25, 1972 SELECTIVE NICKEL DEPOSITION [56] References Cited [72] Inventors: Warren H. Philipp, North Olmsted; Stan- UNITED TATE-S PATENTS ley J. Marsik, Fairview Park; Charles E. May, Rocky River, all of Ohio 1,207,218 12/1916 Roux ..148/6.l5 [73] Assignee: The United States of America as g i "fig 3 represented by the Administrator 01' the 3336l59 8/1967 is a: H7/933 N alA ds Ad L z: pace 3,492,151 1/1970 Cesc0n..... ....117/93.3 3,513,015 5/1970 Fitzpatrick .117/138.8 Flled! 1969 3,529,961 9/1970 Schaefer et a]. ..117/93.3

21 Appl. No.: 876,588

Primary Examiner-W1ll1am D. Martm Assistant Examiner-William R. Trenor [52] US. Cl. ..1 17/47 R, 96/362, 117/37, '1- Musial G E Shook and G. T. McCoy 117/93.3,117/62, 117/152,l17/124 C,117/l6 R,

204/49, 204/157.l8 AG, 250/65 F A T [51] Int. Cl. ..B4lm 5/00, C030 17/10 [57] ABSTR C [58] Field of Search ..1l7/47,93.3, 138.8, 130 E, A process for selectively depositing nickel by irradiating 117/160 R, 1.7, 62, 152, 124 C; 96/361; 204/49, 157.18 AG; 250/65 F selected portions of a substrate coated with an irradiation sensitive compound. immersing the irradiated substrate in a developer deposits controlled amounts of nickel in the selected portions.

9 Claims, No Drawings SELECTIVE NICKEL DEPOSITION ORIGIN OF THE INVENTION The invention described herein was made by employees of the United States Government and may be manufactured and used by or for the Government for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention is concerned with a radiation-chemical process for depositing nickel. The invention is particularly directed to an improved photographic process in which nickel is deposited in controlled amounts by the irradiation of nickel hypophosphite. The invention also relates to an improved process for making printed circuits.

Conventional photographic processes use silver halides. This material is expensive, and sometimesit may be in short supply. Silver halide treated paper is sensitive to ordinary light, and care must be taken in storing this'photographic paper.

SUMMARY OF THE INVENTION These problems have been solved by thepresent invention. A suitable substrate coated with nickel hypophosphite is irradiated to cause a chemical change. Nickel is deposited only on the irradiated areas by immersing the substrate in a developing solution. The density of the nickel deposit is a function of irradiation dose within a particular dose range.

OBJECTS OF THE INVENTION It is, therefore, an object of the present invention to provide a method of depositing nickel throughout porous substrates.

Another object of the invention is to provide a process for the selective deposition of nickel on various substrates suitable for making printed circuits or the like.

A further object of the invention is to form permanent nickel images or prints with wide tonal gradations throughout the gray scale.

A still further object of the invention is to provide catalysts by depositing nickel in porous substrates, such as fritted-glass, blotting paper and porous ceramics.

These and other objects and advantages of the invention will be apparent from the specification which'follows.

DESCRIPTION or THE PREFERREDEMBODIMENT According to the present invention a suitable substrate, such as filter paper, blotting paper, or glass carries a nickel compound that is sensitive to irradiation. This substrate is first prepared by coating or impregnating with a solution containing nickel hypophosphite. The coated substrate is then dried.

The dry coated substrate is irradiated within a certain chosen range. This is preferably accomplished by subjecting the dry substrate to ionizing radiation, such as X-rays orelectrons. A change occurs in the nickel hypophosphite as a result of this irradiation. This change is similar tothat whichoccu'rs when silver halide photographic emulsions are exposed to light to form latent images. As a result, deposition of the nickel on the exposed areas is accomplished upon contact with a developing solution.

The developer is composed of ammoniacal nickel-salt solution containing a hypophosphite ion. However, if a catalytically active nickel is desired, the developer is simply dilute aqueous ammonia.

The nickel deposits only in the areas exposed to radiation. By using a suitable mask that is opaque to radiation, selective deposition of nickel on a substrate can be accomplished to provide printed circuits.

Test samples were prepared to better illustrate the invention. In the first sample, filter paper of medium porosity was dipped in a solution having the followin'gcon'iposition:

Nickel hypophosphite Concentrated aqueous ammonia (28 to 30% NHn) Mucilage l8 ml.

Nickel (ll) Sulfate or Nickel (ll) 7 Chloride O.l molar Sodium Hypophosphite NaHJO, 0.2 molar Ammonia 1.0 molar The development of an image was complete in less than l minute. After development the paper containing the nickel image was washed in water to remove excess developer. The image exhibited tonal gradations'according to the thickness of thernask.

The treated filter paper was given a short exposure of less than 30 seconds to l MeV'electrons at a beam density of about 0.5 microamp per square centimeter. This produced an image similar to that produced by the KV X-rays.

In another sample the filter paper treated as described in the first sample was masked with a fine wire screen and exposed to 65 KV X-rays. Upon development a sharp, finely detailed image formed in the exposed areas.

A pattern was made by removing lead oxide from a lead oxide coated filter paper. The resulting pattern was used as a mask.Using the same procedure as in the'previous samples a sharp black nickel image of the scratched pattern was obtained.

A smooth glass plate was coated by brushing on the nickel hypophosphite solution prepared in the first example. The coated plate was permitted to dry at room temperature. The dry coated'plate was exposed to 65 KV X-rays and developed as in Example 1. A strong adherent nickel mirror formed on the glass plate. This mirror had the ability of being polished on the coated side.. Similar results were obtained using 1 MeV electrons as a radiation source.

Catalytically active nickel distributed throughout a thick blotting paper was obtained by immersing the blotting paper in the following solution:

Nickel hypophosphite Ni(H;PO,) '6H,O l0 grams Concentrated aqueous ammonia (28 to 30% NH;,) 25 ml.

The blotting paper was allowed to dry at room temperature. The dry treated specimen was irradiated with 1 MeV electrons for about 30 minutes with a current density of about 0.5 microamp per-square centimeter. The irradiated paper was then developed in dilute aqueous ammonia which caused the deposition of the nickel by decomposition of the irradiated nickel hypophosphite already present in the substrate. The blotting paper containing the active nickel showed good catalytic properties in promoting the 'Cannizzaro reaction and in "the decomposition of alkaline sodium hypophosphite solutions. A typical analysis of the nickel impregnated blotting paper prepared by this method showed it contained 56 percent nickel by weight.

What is claimed is: I

'1. A method of forming permanent nickel prints in an improved photographic process comprising the steps of coating a substrate with an irradiation sensitive nickel hypophosphite solution,

drying said coated substrate,

irradiating predetermined portions of said substrate to form a latent image, and

contacting said irradiated substrate with a developing solution to deposit nickel in said predetermined portions.

2. A method 'as claimed in claim 1 wherein the substrate is ceramic.

3. A method as claimed in claim 1 wherein the substrate is orous aper.

containing a hypophosphite ion.

8. A method as claimed in claim 1 wherein the developing solution is a solution of dilute aqueous ammonia.

9. A method as claimed in claim 1 including the step of masking predetermined portions of the substrate with a material that is opaque to radiation. 

2. A method as claimed in claim 1 wherein the substrate is ceramic.
 3. A method as claimed in claim 1 wherein the substrate is porous paper.
 4. A method as claimed in claim 1 wherein the substrate is glass.
 5. A method as claimed in claim 1 wherein the irradiation is X-rays.
 6. A method as claimed in claim 1 wherein the irradiation is ionizing particles.
 7. A method as claimed in claim 1 wherein the nickel hypophosphite solution is an ammoniacal nickel-salt solution containing a hypophosphite ion.
 8. A method as claimed in claim 1 wherein the developing solution is a solution of dilute aqueous ammonia.
 9. A method as claimed in claim 1 including the step of masking predetermined portions of the substrate with a material that is opaque to radiation. 